This invention relates to an improved sealing gasket for an air filter, and more particularly, to a sealing gasket for such filter which includes a relatively hard backing portion and a relatively soft sealing portion.
One weakness in a typical carburetor air filter construction is that the gasket does not always effectively seal between the filter and the air filter housing or cover and air may leak between the gasket and the air filter housing or cover and therefore, bypass the filter media. Unfiltered air may reach the carburetor and possibly interfere with operation of the carburetor and/or engine. The leakage may be caused by the housing or cover having a warped or irregular surface
The leakage may be reduced by using a soft gasketing material, however, a soft gasketing material will not have sufficient strength or physical integrity to make a strong bond to the filtering media.
Air filters which comprise a filter media with a gasket affixed at either end of the media are known in the prior art. These filters are commonly made by placing the filter media into a mold, filling the mold with a plastic resin and heating the resin until it becomes a solid mass fused with the filter media. The process is repeated to form a sealing gasket on both sides of the filter media. For example, Rabbit et al. U.S. Pat. No. 2,732,031 discloses a cartridge for an air filter which includes a filter media having gaskets made of vinyl chloride or polyvinyl chloride affixed to opposite ends of the filter media. The gasket of Rabbit et al. is made of material having a uniform durometer or hardness therethrough and thus, is subject to the weaknesses discussed above. Holloway U.S. Pat. No. 3,235,633 and Thronburge U.S. Pat. No. 2,941,620 discloses similar air filters as shown in Rabbit et al. and are representative of the known prior art. It is also known to form filters from a similar process using gasketing material that does not require heating.
The Rodgers U.S. Pat. No. 3,397,518 suggests a seal for an air filter which includes a seal member having an irregular outer surface, however, there is no suggestion that the seal have portions of different durometer in order to provide a better seal between the seal and contact surface.
One object of the present invention is to provide an improved sealing gasket for an air filter which overcomes the disadvantages and deficiencies of prior constructions.
Another object of this invention is to provide a sealing gasket for an air filter which comprises an annular member having a base portion and a seal portion, the base portion having a higher durometer than the seal portion, and means to provide space for the seal portion which may be deformed in use, whereby the seal portion can more readily adapt to the contour of the contract surface so as to provide a better seal between the sealing gasket and such contact surface.
Yet another object of this invention is to provide a sealing gasket for an air filter comprising an annular member having a base portion and a sealing portion, the base portion having a higher durometer than the sealing portion, whereby the sealing portion can more readily adapt to the contour of a contact surface which it may engage so as to provide a better seal between the sealing gasket and such contact surface, said base portion including a generally flat first surface and an opposite surface from which the sealing portion projects, and an annular recess in the said opposite surface in order to provide space for the sealing portion which may be deformed in use. Other objects and advantages of the invention will be made more apparent hereinafter.